The present invention relates to agents for lightening keratinic fibers, particularly human hair, which, in addition to a chemical oxidizing agent, contain at least one specific cationic phthalimide. Use thereof on keratinic fibers significantly improves the lightening power of lightening and blonding agents. The present invention furthermore relates to a multicomponent packaging unit (kit of parts) for lightening keratinic fibers comprising, packaged separately from one another, at least one agent containing a specific cationic phthalimide, an oxidizing agent preparation and optionally a blonding powder.
Modifying the shape and color of hair is an important area of modern cosmetics and allows the appearance of the hair to be adapted both to current fashion trends and to a person's individual wishes. Permanent waves and other methods for modifying hair shape may be applied virtually irrespective of the type of hair treated. In contrast, dyeing and blonding methods are restricted to specific initial hair colors.
Lightening of the natural hair color has long been a desire of many consumers, since blonde hair color is regarded as attractive and desirable from a fashion standpoint. Various blonding agents of variable blonding power are commercially obtainable for this purpose. The oxidizing agents present in these products are capable of lightening the hair fibers by oxidative destruction of the hair's own colorant melanin. To achieve a moderate blonding effect, it is sufficient to use hydrogen peroxide, optionally together with ammonia or other alkalizing agents, as the sole oxidizing agent, while if a stronger blonding effect is desired, it is conventional to use a mixture of hydrogen peroxide and peroxodisulfate salts and/or peroxomonosulfate salts.
Unfortunately, lightening is also accompanied by hair damage as it is not only the hair's colorants which suffer oxidative damage, but also other structural components of the hair. Depending on its extent, damage can vary from rough, brittle and difficult to comb hair via reduced resistance and tensile strength of the hair to hair breakage. In general, the greater the amount of hydrogen peroxide and optional peroxodisulfates used, the more severe will be the damage caused to the keratin fibers. Hair dyes or lightening agents which exhibit good lightening power without simultaneously damaging the hair fibers are hitherto unknown.
It is accordingly an object of the present application to provide novel agents for lightening or blonding hair which are comparable or superior to the conventional agents on the market in their lightening power, while at the same time exhibiting reduced hair damage. For consumers with very dark hair, it is not possible to create light blond shades even when using elevated hydrogen peroxide concentrations in combination with persulfate salts. Repeated applications also cannot be carried out because of increasing levels of hair damage. It is therefore a further object of the present invention to provide an agent having lightening capacity which exceeds that of conventional commercial agents consisting of hydrogen peroxide and peroxodisulfate salts (sodium peroxodisulfate, ammonium peroxodisulfate and/or potassium peroxodisulfate).
EP 508623 A2 discloses specific cationic phthalimide derivatives in the form of the percarboxylic acids thereof which are used in the presence of perborates as bleaching agents in textile bleaching. Use of the corresponding phthalimides in blonding agents for lightening hair is hitherto unknown. When bleaching textiles and lightening hair, different, in some cases greatly different, application parameters are selected, such that the test results from one field of application cannot be transferred to the other. Accordingly, both the formulation and the temperatures to be selected in the two bleaching processes differ greatly. It was therefore not foreseeable from the prior art that the lightening action hair can be enhanced by using cationic phthalimides in cosmetic blonding agents.